You may be used to just starting with a template_info.php file, but now there are a few more steps.

If you get a log like

Code:
PHP Fatal error:  Call to a member function isMobile() on null in ... tpl_shopping_cart_default.php line 66
You need to copy in common (and in particular common/html_header.php which sets the $detect variable).

I suspect you want to also copy in css, menu_templates and jscript and modify from there.